AI agent
An AI agent is a software system that pursues a goal you define by choosing its own sequence of actions and using tools to affect systems outside the conversation.
The distinguishing property is not intelligence but autonomy over the steps: you specify the outcome, and the agent decides how to reach it. A large language model answering a question is doing inference; the same model deciding to search a codebase, edit a file, run the tests, and try again is acting as an agent.
If the sequence of steps is known in advance and does not change, the right thing to build is a fixed workflow rather than an agent — it is cheaper to run and far easier to debug. Agents earn their complexity only when the path genuinely cannot be determined ahead of time.
